Pyridine-Oxyphenyl Coordinated Iridium (III) Complexes and Methods of Making and Using

ABSTRACT

Iridium (III) complexes are described together with methods to prepare and use such complexes. Also described are devices that utilize the iridium (III) complexes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/475,321, filed on Apr. 14, 2011, which is hereby incorporated byreference in its entirety.

BACKGROUND Technical Field

The present disclosure relates to iridium complexes which are capable ofabsorbing and/or emitting light and are thus useful as an emissive orabsorption material in a device.

Technical Background

Compounds capable of absorbing and/or emitting light are ideally suitedfor use in a wide variety of applications, including optical andelectro-optical devices, photo-absorbing devices, and as markers forbio-applications. Much research has been devoted to the discovery andoptimization of organic and organometallic materials for use in suchapplications. Generally, research in this area aims to accomplish anumber of goals, including improvements in absorption and emissionefficiency, as well as improvements in processing ability, among others.

Despite significant advances in research devoted to optical,electro-optical, and marker materials, existing materials have a numberdisadvantages, including poor processing ability, inefficient emissionor absorption, and less than ideal stability, among others. Thus, a needexists for new materials which exhibit improved performance in opticalemitting and absorbing applications. This need and other needs aresatisfied by the present invention.

SUMMARY

The present invention relates to iridium complexes that exhibitphotoabsorption and photoemission, to methods of making such compounds,and to applications thereof, including optical devices comprising thecompounds.

In one aspect, the present invention provides a tetradentate iridium(III) complex represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen, and each Arepresents an ancillary ligand that can be used to balance the charge onthe complex.

In another aspect, the present invention provides a tetradentate iridium(III) complex represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen.

In another aspect, the present invention provides a hexadentate iridium(III) complex represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen.

In still another aspect, the present invention provides a hexadentateiridium (III) complex represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen.

In still another aspect, the present invention provides a hexadentateiridium (III) complex represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen, and each Hrepresent a bridging atom, such as, for example, a halogen, such as achloride.

In yet another aspect, the present invention provides an organiclight-emitting diode (OLED) comprising one or more of the iridium (III)complexes described herein.

In yet another aspect, the present invention provides an organicphotovoltaic device comprising, as a donor or acceptor material, one ormore of the iridium (III) complexes described herein.

In yet another aspect, the present invention provides a luminescentbio-marker comprising one or more of the iridium (III) complexesdescribed herein.

Also disclosed are optical devices, such as organic light emittingdevices, photovoltaic devices (e.g., solar cells), and luminescentdisplay devices that comprise one or more compounds of the invention asa functional material, such as a light-emitter or absorber, or both.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated in and constitute apart of this specification, illustrate several aspects and together withthe description serve to explain the principles of the invention.

FIG. 1 is a drawing of a cross-section of an exemplary organiclight-emitting diode (OLED).

FIG. 2 illustrates the emission spectrum of an Ir003-acac complex atroom temperature in dichloromethane, in accordance with various aspectsof the present invention.

Additional aspects of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or can be learned by practice of the invention. Theadvantages of the invention will be realized and attained by means ofthe elements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION

The present invention can be understood more readily by reference to thefollowing detailed description of the invention and the Examplesincluded therein.

Before the present compounds, devices, and/or methods are disclosed anddescribed, it is to be understood that they are not limited to specificsynthetic methods unless otherwise specified, or to particular reagentsunless otherwise specified, as such can, of course, vary. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular aspects only and is not intended to be limiting.Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of the presentinvention, example methods and materials are now described.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a component”includes mixtures of two or more components.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint. It is also understood that there are a number of valuesdisclosed herein, and that each value is also herein disclosed as“about” that particular value in addition to the value itself. Forexample, if the value “10” is disclosed, then “about 10” is alsodisclosed. It is also understood that each unit between two particularunits are also disclosed. For example, if 10 and 15 are disclosed, then11, 12, 13, and 14 are also disclosed.

As used herein, the terms “optional” or “optionally” means that thesubsequently described event or circumstance can or can not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

The term “alkyl” as used herein is a branched or unbranched saturatedhydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl,isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, and the like. The alkylgroup can be cyclic or acyclic. The alkyl group can be branched orunbranched. The alkyl group can also be substituted or unsubstituted.For example, the alkyl group can be substituted with one or more groupsincluding, but not limited to, optionally substituted alkyl, cycloalkyl,alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, orthiol, as described herein. A “lower alkyl” group is an alkyl groupcontaining from one to six (e.g., from one to four) carbon atoms.

The terms “amine” or “amino” as used herein are represented by theformula NA¹A²A³, where A¹, A², and A³ can be, independently, hydrogen oroptionally substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl,alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “halide” as used herein refers to the halogens fluorine,chlorine, bromine, and iodine.

The term “hydroxyl” as used herein is represented by the formula —OH.

The term “nitro” as used herein is represented by the formula —NO₂.

The term “nitrile” as used herein is represented by the formula —CN.

The term “thiol” as used herein is represented by the formula —SH.

Disclosed are the components to be used to prepare the compositions ofthe invention as well as the compositions themselves to be used withinthe methods disclosed herein. These and other materials are disclosedherein, and it is understood that when combinations, subsets,interactions, groups, etc. of these materials are disclosed that whilespecific reference of each various individual and collectivecombinations and permutation of these compounds can not be explicitlydisclosed, each is specifically contemplated and described herein. Forexample, if a particular compound is disclosed and discussed and anumber of modifications that can be made to a number of moleculesincluding the compounds are discussed, specifically contemplated is eachand every combination and permutation of the compound and themodifications that are possible unless specifically indicated to thecontrary. Thus, if a class of molecules A, B, and C are disclosed aswell as a class of molecules D, E, and F and an example of a combinationmolecule, A-D is disclosed, then even if each is not individuallyrecited each is individually and collectively contemplated meaningcombinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considereddisclosed. Likewise, any subset or combination of these is alsodisclosed. Thus, for example, the sub-group of A-E, B-F, and C-E wouldbe considered disclosed. This concept applies to all aspects of thisapplication including, but not limited to, steps in methods of makingand using the compositions of the invention. Thus, if there are avariety of additional steps that can be performed it is understood thateach of these additional steps can be performed with any specificembodiment or combination of embodiments of the methods of theinvention.

As briefly described above, the present invention is directed to iridiumcomplexes, such as, for example, iridium (III) complexes. In one aspect,the invention comprises a tetradentate iridium (III) complex. In anotheraspect, the invention comprises a hexadentate iridium (III) complex. Inyet another aspect, the emission energy of an inventive iridium complexcan be adjusted by modifying one or more of the ligands coordinated tothe iridium metal center. In another aspect, the invention comprises aniridium atom coordinated with one or more tetradentate ligands,hexadentate ligands, or a combination thereof.

As used herein, references to “C”, “E”, “A”, and “N” are intended torefer to moieties or functions groups on the described complex. In oneaspect, reference to a “C” or an “N” can refer to a moiety comprisingsuch an atom, for example, a carbon or nitrogen, respectively. Inanother aspect, reference to a “C” or an “N” can refer to a moiety asdescribed herein

The inventive iridium complexes of the present disclosure can, invarious aspects, exhibit phosphorescent properties. In another aspect,the emission spectrum of an iridium complex can be tuned, for example,so as to provide a desired color for a particular application. In suchan aspect, the emission spectrum can be tuned, for example, from theultraviolet to the near infrared by modifying the ligand structure ofthe complex.

In another aspect, the inventive iridium complexes have improvedstability and efficiency over traditional emission complexes. In yetanother aspect, the inventive iridium complexes can be useful asluminescent labels in, for example, bio-applications, anti-canceragents, photovoltaic absorbers, emitters in organic light emittingdiodes (OLED), or a combination thereof.

In one aspect, each C represents a moiety comprising 1-10 carbon atoms.For example, the moiety can comprise 6 carbon atoms. In another aspect,the carbon atoms can form a ring structure, such as an aromatic ringstructure. Suitable moieties include, but are not limited to,substituted and unsubstituted aryl or cycloalkyl, preferably substitutedand unsubstituted aryl. In one aspect, the aryl can be substituted andunsubstituted phenyl. In another aspect, the aryl can be unsubstitutedphenyl. Unsubstituted phenyl refers to a structure that is notsubstituted except for the linkages to other moieties as show in theformulas disclosed herein. For example, a phenyl without furthersubstitutions bonded to X, C and N as shown in the formulas describedherein is an unsubstituted aryl or phenyl. Substituted aryl, forexample, refers to an aryl group that can be substituted with one ormore groups including, but not limited to, optionally substituted alkyl,cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl,sulfo-oxo, or thiol, as described herein. In other aspects, C canrepresent other moieties not specifically recited herein, but that aredescribed in any of the structures, figures, or examples providedherein, or that one of skill in the art would contemplate as a variant,analog, and/or suitable structure for an intended application

In one aspect, N represents a moiety comprising 1-10 atoms, wherein inat least one atom is nitrogen and the remaining atoms are either carbon,nitrogen, oxygen or sulfur atoms. For example, the moiety can compriseone nitrogen atom and three, four or five carbon atoms. In antherexample, the moiety can comprise two nitrogen atoms and two, three orfour carbon atoms. The moiety can be a ring structure. In one aspect,the ring structure is aromatic. In another aspect, the ring structure isnot aromatic. The ring structures can be substituted or unsubstituted.Substituted N moieties include substitutions with one or more groupsincluding, but not limited to, optionally substituted alkyl, cycloalkyl,alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, orthiol, as described herein. In one aspect, one or two carbon atoms inthe N moiety can be substituted with an alkyl group. Suitable N moietiesinclude, but are not limited to substituted and unsubstituted pyridine,pyrrole, pyrazole, imidazole, and triazole. In one aspect, a nitrogenatom in the N moiety can be bonded to X. In other aspects, N canrepresent other moieties not specifically recited herein, but that aredescribed in any of the structures, figures, or examples providedherein, or that one of skill in the art would contemplate as a variant,analog, and/or suitable structure for an intended application.

In one aspect, if two or more N moieties are present in a complex andleast one of the E bridging groups can be present, and can be oxygen. Inanother aspect, if two or more N moieties are present in a complex andall E bridging groups can be present, and can be oxygen.

In one aspect, at least one, two or three E bridging atoms can bepresent in the complex. For example, one, two, three, four or five Ebridging atoms can be present in the complex. In one aspect, all Ebridging atoms shown in the complex are present. In one aspect, at leastone, two or three E bridging atoms shown in the complexes are notpresent. In one aspect, one, two, three or four E bridging atoms shownin the complexes are not present. In one aspect, each E bridging atomcan be oxygen. In one aspect, at least two E bridging atoms are oxygen,for example, the complex can comprise two, three, four or five Ebridging oxygen atoms.

In one aspect, A can be a moiety comprising 1-10 atoms, wherein theatoms are either carbon, nitrogen, oxygen or sulfur atoms. In oneaspect, at least one A moiety comprises an oxygen atom bonded to X inthe complex. In one aspect, both A moieties, when present, comprise anoxygen atom bonded to X in the complex. In one aspect, the A moietiescan have different structures. In another aspect, the A moieties canhave the same structure. In one aspect, the A moieties bonded to X formsa ring structure. For example, the ring structure can comprise 4-10atoms, preferably 6 atoms. In one aspect, the A moieties or the linkagebetween the A moieties can comprise a carbon-carbon double bond. In oneaspect, the A moities can be substituted with one or more groupsincluding, but not limited to, optionally substituted alkyl, cycloalkyl,alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, orthiol, as described herein.

In one aspect, the present disclosure provides a tetradentate iridium(III) complex. In another aspect, a tetradentate iridium (III) complexcan be represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen, and each Arepresents an ancillary ligand that can be used to balance the charge onthe complex.

In one aspect, it should be understood that where multiple references toa ligand exist, for example, two A ligands exist in the structure above,each of the plurality of references can refer to the same or a differentligand. For example, in the structure illustrated above, each A canrefer to the same or a different ancillary ligand

In another aspect, a hexadentate iridium (III) complex can berepresented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen.

In various exemplary aspects, a tetradentate iridium (III) complex cancomprise one or more of the following structures:

a combination thereof.

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In another aspect, the inventive composition can comprise a mixture ofone or more of the complexes described herein. In yet another aspect,the inventive composition can exclude, and thus, not comprise any one ormore of the complexes described herein. In still other aspects, theinventive composition can comprise one or more of the complexesdescribed herein in addition to other compounds suitable for use in adesired application.

In one aspect, the present disclosure provides a hexadentate iridium(III) complex. In another aspect, a hexadentate iridium (III) complexcan be represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen.

In another aspect, a hexadentate iridium (III) complex can berepresented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen.

In various exemplary aspects, a hexadentate iridium (III) complex cancomprise one or more of the following structures:

or a combination thereof.

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In one aspect, the iridium (III) complex comprises:

In still another aspect, the present invention provides a hexadentateiridium (III) complex represented by the formula:

wherein X represents an iridium atom, each C represents a carbon moiety,each N represents a nitrogen moiety, each E represents an optionalbridging atom, such as, for example, carbon or oxygen, and each Hrepresent a bridging atom, such as, for example, a halogen, such as achloride.

In one aspect, the H can be a bridging atom, such as a halogen bridgingatom. The halogen can be fluoride, chloride, iodine or bromide. Forexample, the halogen bridging atom can be chloride.

In one aspect, the iridium (III) complex comprises:

The compounds of the invention can be made using a variety of methods,including, but not limited to those recited in the examples providedherein. In other aspects, one of skill in the art, in possession of thisdisclosure, could readily determine an appropriate method for thepreparation of an iridium complex as recited herein.

The compounds of the invention are useful in a variety of applications.As light emitting materials, the compounds can be useful in organiclight emitting diodes (OLED)s, luminescent devices and displays, andother light emitting devices, or as luminescent markers inbio-applications.

The emission (and absorption) profile of the compounds can be tuned byvarying the structure of the ligand surrounding the metal center. Forexample, compounds having a ligand with electron withdrawingsubstituents will generally exhibit different optical properties,including emission and absorption, than compounds having a ligand withelectron donating substituents. Generally, a chemical structural changeaffects the electronic structure of the compound, which thereby affectsthe absorption and emission of the compound. Thus, the compounds of thepresent invention can be tailored or tuned to a specific applicationthat desires a particular emission or absorption characteristic.

In one embodiment, the compounds can be used in an OLED. FIG. 1 shows across-sectional view of an OLED 100, which includes substrate 102 withan anode 104, which is typically a transparent material, such as indiumtin oxide, a layer of hole-transporting material(s) (HTL) 106, a layerof light processing material 108, such as an emissive material (EML)including an emitter and a host, a layer of electron-transportingmaterial(s) (ETL) 110, and a metal cathode layer 112.

In this embodiment, the layer of light processing material 108 cancomprise one or more compounds of the present invention optionallytogether with a host material. The host material can be any suitablehost material known in the art. The emission color of an OLED isdetermined by the emission energy (optical energy gap) of the lightprocessing material 108, which as discussed above can be tuned by tuningthe electronic structure of the emitting compounds and/or the hostmaterial. Both the hole-transporting material in the HTL layer 106 andthe electron-transporting material(s) in the ETL layer 110 can compriseany suitable hole-transporter known in the art. A selection of which iswell within the purview of those skilled in the art.

It will be apparent that the compounds of the present invention canexhibit phosphorescence. Phosphorescent OLEDs (i.e., OLEDs withphosphorescent emitters) typically have higher device efficiencies thanother OLEDs, such as fluorescent OLEDs. Light emitting devices based onelectrophosphorescent emitters are described in more detail inWO2000/070655 to Baldo et al., which is incorporated herein by thisreference for its teaching of OLEDs, and in particular phosphorescentOLEDs.

Also disclosed herein are methods of making the iridium (III) complexes.In one aspect, the iridium (III) complexes can be made by syntheticmethods described herein. Each of the complexes described herein can beproduced by the methods described herein and/or can be produced by oneof skill in the art, in possession of this disclosure, using methodsknown in the art.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how thecompounds, compositions, articles, devices and/or methods claimed hereinare made and evaluated, and are intended to be purely exemplary of theinvention and are not intended to limit the scope of what the inventorsregard as their invention. Efforts have been made to ensure accuracywith respect to numbers (e.g., amounts, temperature, etc.), but someerrors and deviations should be accounted for. Unless indicatedotherwise, parts are parts by weight, temperature is in ° C. or is atambient temperature, and pressure is at or near atmospheric.

Example 1 Preparation of Ir-003-acac

a) Synthesis of Py-O-Ph-OH

Under a nitrogen atmosphere, a pressure vessel was charged with amagnetic stir bar, resorcinol (110 mmol), 2-bromopyridine (100 mmol),1-methylimidazole (5 mmol), and potassium carbonate (200 mmol). Pyridine(80 mL) was added and bubbled with nitrogen for 20 minutes beforecopper(I) iodide (10 mmol) was added and bubbled 10 minutes further. Thevessel was then sealed and heated to 140° C. while stirring. After 2days, the solution was allowed to cool. The solids were filtered off andrinsed with a 50:50 mixture of toluene and methanol. The filtrate wasconcentrated under reduced pressure and 150 ml of water containing 10 mLglacial acetic acid was added and shaken vigorously. The water wasdecanted off and 50 mL of dichloromethane (DCM) was added, forming anoff white precipitate which was collected by vacuum filtration and driedwith ether, resulting in the pure product Py-O-Ph-OH with a 55% yield.¹H NMR (CDCl₃): 5.98 (s, 1H), 6.59 (s, 1H), 6.62-6.69 (m, 2H), 6.94 (d,1H), f 7.02 (dd, 1H), 7.23 (vt, 1H), 7.70 (dd, 1H), 8.23 (b, 1H).

b) Synthesis of Py-O-Ph-O-Py-Br

Under a nitrogen atmosphere, a pressure vessel was charged with amagnetic stir bar, Py-O-Ph-OH (50 mmol), 2,6-dibromopyridine (50 mmol),1-methylimidazole (25 mmol), and potassium carbonate (100 mmol). Toluene(80 mL) was added and bubbled with nitrogen for 20 minutes beforecopper(I) iodide (5 mmol) was added and the solution bubbled for 10minutes further. The vessel was sealed and heated to 140° C. whilestirring. After 2 days, the solution was allowed to cool and the solidswere filtered off and rinsed with dichloromethane. The filtrate wasadded to a separatory funnel containing DCM and water. The water phasewas washed 3 times with 75 mL DCM, and the combined organic layers werewashed once with pure water. The organic layer was collected, dried withmagnesium sulfate, filtered, and the filtrate concentrated under reducedpressure. The resulting oil was purified by column chromatography usingDCM over silica resulting in the pure product Py-O-Ph-O-Py-Br with a 60%yield. ¹H NMR (CDCl₃): 6.80-6.85 (m, 2H), 6.91 (s, 1H), 6.94 (s, 1H),6.97-7.03 (m, 2H), 7.19 (vt, 1H), 7.21-7.24 (m, 2H), 7.36 (vt, 1H), 7.70(dd, 1H), 8.21 (dd, 1H).

c) Synthesis of Py-O-Ph-O-Ph-Py

Under a nitrogen atmosphere, an oven dried three neck flask was chargedwith a magnetic stir bar, Py-O-Ph-O-Ph-Br (10 mmol), and2-(tripropylstannyl)pyridine (10 mmol). Dry toluene (100 mL) was addedand bubbled with nitrogen for 20 minutes beforeTetrakis(triphenylphosphine)palladium(0) (0.5 mmol) was added, bubbled10 minutes further, and brought to reflux for 2 days. After cooling, thecontents of the flask were filtered, the liquid concentrated underreduced pressure, and the resulting oil was purified by columnchromatography using DCM over silica to yield the pure productPy-O-Ph-O-Ph-Py with a 65% yield. ¹H NMR (CDCl₃): 6.84 (vt, 1H),6.85-6.89 (m, 2H), 6.91 (d, 1H), 6.98 (dd, 1H), 7.11 (dd, 1H), 7.24 (dd,1H), 7.34 (vt, 1H), 7.44 (vt, 1H), 7.66-7.78 (m, 5H), 8.19 (dd, 1H),8.67 (dd, 1H).

d) Synthesis of [(Py-O-Ph-O-Ph-Py)Ir(μ-cl)]₂

Under a nitrogen atmosphere, three neck flask was charged with amagnetic stir bar, Py-O-Ph-O-Ph-Py (10 mmol), and IrCL3.H₂O (10 mmol).2-ethoxyethanol (20 mL) was added brought to 80° C. for 1 day. Aftercooling, the contents of the flask were concentrated under reducedpressure. DCM was added, stirred for 10 minutes, and filtered by vacuumfiltration. The filtrate was collected, dried with magnesium sulfate andconcentrated under reduced pressure, producing an off-white solid.

e) Synthesis of Ir-003-acac

A round bottom flask was charged with [(Py-O-Ph-O-Ph-Py)Ir(μ-cl)]₂ (10mmol), acetyl acetone (15 mmol), potassium carbonate (20 mmol), and1,2-dichoroethane (20 mL). The mixture was stirred overnight at 80° C.After cooling the mixture was filtered, the filtrate collected, andconcentrated under reduced pressure. The resulting solid was purified bycolumn chromatography using DCM over silica to yield Ir-003-acac. FIG. 2illustrates the emission spectrum of the prepared Ir003-acac complex, atroom temperature and in dichloromethane.

1. A multidentate iridium (III) complex represented by one of thefollowing general formulas:

wherein: X represents an iridium atom, each C in General Formula 2 and 3represents a phenyl moiety, or each C in General Formula 1 represents aphenyl or pyridinyl moiety; each N in General Formula 1 and 2 representsa pyridyl, pyrrolyl, pyrazolyl, or imidazolyl moiety, or each N inGeneral Formula 3 represents a phenyl, pyridyl, pyrrolyl, pyrazolyl, orimidazolyl moiety; each E represents a covalent bond, a CH₂ moiety, oran oxygen atom, and at least one E represents an oxygen atom; and each Ain General Formula 1 represents a phenyl or pyridyl moiety, or A-Arepresents an acetylacetonyl moiety.
 2. The multidentate iridium (III)complex of claim 1, wherein General Formula 1 is a tetradentate iridium(III) complex.
 3. (canceled)
 4. The multidentate iridium (III) complexof claim 2, wherein each N represents a pyridyl or imidazolyl moiety. 5.The multidentate iridium (III) complex of claim 2, wherein two E arepresent and represent oxygen atoms.
 6. The multidentate iridium (III)complex of claim 1, wherein General Formula 2 is a hexadentate iridium(III) complex. 7-8. (canceled)
 9. The multidentate iridium (III) complexof claim 6, wherein two E are present and represent oxygen atoms. 10.The multidentate iridium (III) complex of claim 1, wherein GeneralFormula 3 is a hexadentate iridium (III) complex. 11-12. (canceled) 13.The multidentate iridium (III) complex of claim 10, wherein two E arepresent and represent oxygen atoms. 14-20. (canceled)
 21. An organiclight-emitting diode (OLED) comprising one or more of the multidentateiridium (III) complexes of claim
 1. 22. An organic photovoltaic devicecomprising, as a donor or acceptor material, one or more of themultidentate iridium (III) complexes of claim
 1. 23. A luminescentbio-marker comprising one or more of the multidentate iridium (III)complexes of claim
 1. 24. (canceled)
 25. The multidentate iridium (III)complex of claim 1, wherein each E represents an oxygen atom or acovalent bond.
 26. The multidentate iridium (III) complex of claim 25,wherein at least three E represent oxygen atoms.
 27. The multidentateiridium (III) complex of claim 26, wherein at least four E of GeneralFormula 3 represent oxygen atoms.
 28. The multidentate iridium (III)complex of claim 1, wherein each E represents an oxygen atom.
 29. Themultidentate iridium (III) complex of claim 1, wherein at least three Erepresent oxygen atoms.
 30. The multidentate iridium (III) complex ofclaim 1, wherein at least four E of General Formula 3 represent oxygenatoms.
 31. The multidentate iridium (III) complex of claim 1, whereinone of the N of General Formula 3 represents a phenyl moiety.
 32. Themultidentate iridium (III) complex of claim 1, wherein one of the C ofGeneral Formula 1 represents a pyridinyl moiety.
 33. The multidentateiridium (III) complex of claim 1, wherein the complex is